In the manufacture of wall blocks and other kinds of blocks made from concrete, it is common to use a mold that forms a block module which is then split to form two or more blocks. When a block module is split, the split surface has an irregular appearance, which is desirable if the desired look is one of natural stone. A split block appearance has a desirable appearance for many applications, such as retaining walls and landscaping products.
A typical wall block has substantially parallel top and bottom surfaces and substantially parallel front and back surfaces. Side surfaces may have various angles or contours relative to the front and back surfaces, or could also be substantially parallel. In forming block modules of such blocks, it is often standard practice to split a block module on a plane coincident with the front faces of two blocks, thus giving the front faces of two opposing blocks an irregular (i.e., roughened) appearance.
U.S. Pat. No. 5,827,015 describes the conventional dry cast manufacturing process used to manufacture concrete wall blocks. In such process, a mold box is used to form a slab that is subsequently split into two wall blocks. It is also known to provide mold boxes which can simultaneously form multiple slabs of identical size and shape.
Another important feature of wall blocks and blocks used in either retaining walls or free standing walls is the appearance of the block. Specifically, it is desirable that exposed portions of the blocks which form the wall have a visually pleasing appearance. The look of weathered natural stone is very appealing for walls. There are several methods in the art to produce concrete wall blocks having an appearance that to varying degrees mimics the look of natural stone. One well known method is to split the block during the manufacturing process so that the front face of the block has a fractured concrete surface that looks like a natural split rock. This is done by forming a slab in a mold and providing one or more grooves in the slab to function as one or more splitting planes. The slab is then split apart to form two or more blocks. Another method is wherein blocks are individually formed in a mold and the surfaces are textured by removal of the mold. Additional machine texturing processes can then be applied. Many manufacturers also vary the color and the texture or pattern on the front face of the block. It might be desirable for the face of the block to be smooth, serrated, or grooved or to have an aggregate appearance.
Another method to create a weathered stone appearance is to tumble the blocks together with other blocks in a large rotating canister. The collisions of the blocks in the tumbler chips off random pieces of the blocks, rounding the edges and creating a look that can be quite close to the appearance of a natural stone. This is a labor intensive undertaking that also can result in undesirable damage to the blocks and high overall costs of production.
Another known method of creating a block having one or more irregular or textured surfaces is to form the block in a mold box that has been provided with a sidewall liner shaped to impart the irregular or textured surface on the block during the block molding process. The block is formed in a cavity bounded by a pallet upon which the mold box rests and the sidewalls of the mold box. After the material which forms the block has set enough to retain its shape a compression head having a stripper shoe positioned above the top of the mold box is used to compress the material and urge it out through the bottom of the mold box. The block remains on the pallet and is moved to a curing station. Additionally or alternatively, the sidewalls of the mold box, especially those provided with a textured or patterned sidewall liner, may be moveable away from the block material before it is removed from the mold box.
Various block systems used to make retaining walls or free standing walls are known in the art. Since only one surface or face of blocks used to form retaining walls is exposed only the exposed surface need be formed with a texture or pattern in order for the wall to have a desired patterned or textured appearance. In freestanding walls both sides of the wall are exposed. Therefore, if it is desired that both sides of the wall have a textured or patterned appearance than the blocks forming the wall must be formed with opposing textured or patterned surfaces on the surfaces which will be exposed. These blocks systems can be used to form walls which are straight or curved gradually inwardly or outwardly and which maintain the desired textured or patterned appearance along the exposed wall surface. Difficulties arise, however, when it is necessary or desirable to construct the wall with a corner. It is desirable that the corners of the wall continue or maintain the same visual appearance that is created by the straight or gradually curved portions of the wall. Typically, the blocks used to form the straight or curved wall surfaces are not configured to form corners such as 90 degree corners. For example, although these blocks are textured or patterned on the exposed face the adjacent side surface of the block which would be exposed at a corner of the wall is not similarly textured or patterned. Additionally, these block systems usually include some way of connecting adjacent courses of blocks such as flanges or pins. With known prior art block systems substantial modifications are typically required in the field by the installers in order to form a corner. Portions of the blocks may need to be cut away by the installer and other modifications to the connection system made in order to make the blocks work at a corner. Even with such field modifications it is extremely difficult to maintain both the desired outward visual appearance of the wall and wall stability at the corners.
Therefore, there is a need in the art for a block that can be used in the formation of a corner that has two surfaces with a texture that is similar to blocks used in the construction of the rest of the wall.
Additionally there is a need in the art for a block that can be used in the formation of a corner for multiple wall systems and that could be molded with a texture substantially similar to the blocks of the wall system it is being applied.
Additionally there is a need in the art for a block that can be used in the formation of a corner for multiple wall systems and having a connection system compatible with the wall system being used.
Additionally there is a need in the art for a block that can be used in the formation of a corner for multiple wall systems to create a consistent and precise running bond pattern for both segments of the wall formed with the corner.